Drucella Andersen
Headquarters, Washington, D.C.
February 10, 1994
(Phone: 202/358-4701)
Linda S. Ellis
Lewis Research Center, Cleveland
(Phone: 216/433-2900)
RELEASE: 94-24
HIGH-SPEED AIRCRAFT RESEARCH COMBUSTOR TESTS EXCEED GOAL
NASA-industry research experiments to reduce exhaust
emissions to environmentally compatible levels for future
supersonic airliners have yielded results that substantially
exceed program goals.
The tests, which used an engine fuel combustion chamber
sector, representing about one-fifth of a full-scale design, beat
NASA's goal of generating no more than 5 grams of oxides of
nitrogen (NOx) per kilogram of fuel burned at supersonic flight
speed.
Scientific studies suggest that a fleet of future supersonic
airliners, equipped with these ultra-low NOx engine combustors,
possibly would have relatively small effects on stratospheric
ozone.
"Protecting Earth's stratospheric ozone layer is our highest
priority," said Louis J. Williams, Director of the High-Speed
Research Program at NASA Headquarters, Washington, D.C., "so
developing the technology to assure environmental compatibility
for future supersonic airliners is the most important goal of our
program."
"The results of these initial ultra-low emissions combustor
tests make us more confident that we'll achieve that goal,"
Williams added.
The combustor sector evaluated was a "Lean Premixed
Prevaporized" concept designed by GE Aircraft Engines, Evendale,
Ohio. It mixes fuel and air upstream of the burning zone and
allows enough time for the liquid fuel to vaporize completely
before combustion.
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The fuel-air mixture then enters the combustion system and
ignites downstream of a flame stabilizer where the speed of the
mixture flow is somewhat slower.
"The ultra-low levels of nitrogen oxide we've achieved in
these tests are extremely encouraging. It shows that the
ultra-low levels we previously saw in the laboratory can
transition to combustor hardware," said Richard W. Niedzwiecki,
Chief of the Combustion Technology Branch, Propulsion Systems
Division at NASA's Lewis Research Center, Cleveland.
NASA also is testing a "Rich Burn-Quick Quench-Lean Burn"
concept developed by Pratt & Whitney Division of United
Technologies, East Hartford, Conn. This design uses two
combustion stages to reduce NOx production.
First, excess fuel is put into a small amount of air. This
"rich burn" environment causes chemical reactions that minimize
NOx emissions. As the mix flows through the combustor, more air
is added and combustion is completed in a final fuel-lean burning
stage. Experimental work with this concept has been started.
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